SELECT 
  SQL_CALC_FOUND_ROWS (
    CASE WHEN products.parent_product_id <> 0 THEN products.parent_product_id ELSE products.product_id END
  ) AS product_id, 
  descr1.product as product, 
  companies.company as company_name, 
  COALESCE(
    cscart_master_products_storefront_min_price.price, 
    MIN(
      IF(
        prices.percentage_discount = 0, 
        prices.price, 
        prices.price - (
          prices.price * prices.percentage_discount
        )/ 100
      )
    )
  ) as price, 
  GROUP_CONCAT(
    products.product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_ids, 
  GROUP_CONCAT(
    products.product_type 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_types, 
  GROUP_CONCAT(
    products.parent_product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS parent_product_ids, 
  products.product_type, 
  products.parent_product_id, 
  products.master_product_offers_count, 
  products.master_product_id, 
  products.company_id, 
  IF(
    products.age_verification = 'Y', 
    'Y', 
    IF(
      cscart_categories.age_verification = 'Y', 
      'Y', cscart_categories.parent_age_verification
    )
  ) as need_age_verification, 
  IF(
    products.age_limit > cscart_categories.age_limit, 
    IF(
      products.age_limit > cscart_categories.parent_age_limit, 
      products.age_limit, cscart_categories.parent_age_limit
    ), 
    IF(
      cscart_categories.age_limit > cscart_categories.parent_age_limit, 
      cscart_categories.age_limit, cscart_categories.parent_age_limit
    )
  ) as age_limit, 
  1 as instock_marker, 
  IF(
    products.product_type = 'C', 
    (
      SELECT 
        MAX(amount) 
      FROM 
        cscart_products 
      WHERE 
        parent_product_id = products.product_id
    ) > 0, 
    IF(
      IF(
        products.tracking = 'O', 
        (
          SELECT 
            MAX(amount) 
          FROM 
            cscart_product_options_inventory s_inventory 
          WHERE 
            s_inventory.product_id = products.product_id
        ) > 0, 
        products.amount > 0
      ), 
      1, 
      IF(products.tracking = 'D', 1, 0)
    )
  ) as instock_sorting 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'en' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  AND cscart_categories.storefront_id IN (0, 3) 
  LEFT JOIN cscart_warehouses_sum_products_amount as war_sum_amount ON war_sum_amount.product_id = products.product_id 
  LEFT JOIN cscart_master_products_storefront_offers_count AS master_products_storefront_offers_count ON master_products_storefront_offers_count.product_id = products.product_id 
  AND master_products_storefront_offers_count.storefront_id = 3 
  LEFT JOIN cscart_master_products_storefront_min_price ON cscart_master_products_storefront_min_price.product_id = prices.product_id 
  AND cscart_master_products_storefront_min_price.storefront_id = 3 
WHERE 
  1 
  AND cscart_categories.category_id IN (
    2706, 
    2707, 
    2724, 
    2728, 
    2729, 
    2730, 
    2731, 
    2732, 
    2733, 
    2755, 
    2756, 
    2757, 
    2758, 
    2759, 
    2760, 
    2761, 
    2762, 
    2763, 
    2764, 
    2765, 
    2768, 
    2769, 
    2770, 
    2771, 
    2772, 
    2773, 
    2774, 
    2775, 
    2776, 
    2777, 
    2780, 
    2781, 
    2782, 
    2783, 
    2784, 
    2785, 
    2786, 
    2787, 
    2788, 
    2789, 
    2790, 
    2791, 
    2792, 
    2793, 
    2794, 
    2795, 
    2801, 
    2851, 
    2852, 
    2853, 
    2854, 
    2855, 
    2856, 
    2857, 
    2858, 
    2859, 
    2860, 
    2861, 
    2862, 
    2863, 
    2864, 
    2865, 
    2866, 
    2867, 
    2868, 
    2869, 
    2870, 
    2937, 
    2938, 
    2939, 
    2940, 
    2941, 
    2942, 
    2943, 
    3008, 
    3009, 
    3010, 
    3011, 
    3016, 
    3017, 
    3018, 
    3019, 
    3020, 
    3021, 
    3028, 
    3029, 
    3030, 
    3031, 
    3032, 
    3033, 
    3034, 
    3035, 
    3036, 
    3038, 
    3039, 
    3040, 
    3041, 
    3042, 
    3044, 
    3055, 
    3056, 
    3057, 
    3058, 
    3059, 
    3060, 
    3061, 
    3062, 
    3063, 
    3064, 
    3065, 
    3066, 
    3067, 
    3068, 
    3069, 
    3070, 
    3071, 
    3072, 
    3073, 
    3074, 
    3075, 
    3076, 
    3077, 
    3078, 
    3079, 
    3080, 
    3081, 
    3082, 
    3083, 
    3084, 
    3085, 
    3086, 
    3087, 
    3088, 
    3089, 
    3090, 
    3091, 
    3092, 
    3093, 
    3094, 
    3095, 
    3096, 
    3097, 
    3098, 
    3099, 
    3100, 
    3101, 
    3102, 
    3103, 
    3104, 
    3105, 
    3106, 
    3107, 
    3108, 
    3109, 
    3110, 
    3182, 
    3183, 
    3184, 
    3185, 
    3186, 
    3187, 
    3188, 
    3189, 
    3289, 
    3291, 
    3292, 
    3293, 
    3294, 
    3295, 
    3296, 
    3297, 
    3298, 
    3299, 
    3300, 
    3301, 
    3302, 
    3303, 
    3304, 
    3305, 
    3306, 
    3307, 
    3308, 
    3309, 
    3310, 
    3311, 
    3312, 
    3313, 
    3314, 
    3317, 
    3318, 
    3319, 
    3320, 
    3321, 
    3322, 
    3323, 
    3324, 
    3325, 
    3326, 
    3327, 
    3328, 
    3329, 
    3330, 
    3331, 
    3332, 
    3344, 
    3345, 
    3346, 
    3347, 
    3348, 
    3349, 
    3350, 
    3351, 
    3352, 
    3353, 
    3354, 
    3355, 
    3356, 
    3357, 
    3358, 
    3359, 
    3360, 
    3361, 
    3362, 
    3363, 
    3414
  ) 
  AND (
    companies.status IN ('A', 'S') 
    OR products.company_id = 0
  ) 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND prices.usergroup_id IN (0, 0, 1) 
  AND products.master_product_status IN ('A') 
  AND products.master_product_id = 0 
  AND (
    products.company_id > 0 
    OR (
      master_products_storefront_offers_count.count > 0
    )
  ) 
  AND products.product_type != 'D' 
GROUP BY 
  product_id 
ORDER BY 
  instock_sorting DESC, 
  price asc, 
  products.product_id ASC 
LIMIT 
  0, 20

Query time 0.08817

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "73.52"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": true,
        "buffer_result": {
          "using_temporary_table": true,
          "nested_loop": [
            {
              "table": {
                "table_name": "war_sum_amount",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "product_id"
                ]
              }
            },
            {
              "table": {
                "table_name": "master_products_storefront_offers_count",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY",
                  "idx_storefront_id"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "storefront_id",
                  "product_id",
                  "count"
                ]
              }
            },
            {
              "table": {
                "table_name": "cscart_master_products_storefront_min_price",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "storefront_id",
                  "product_id",
                  "price"
                ]
              }
            },
            {
              "table": {
                "table_name": "products_categories",
                "access_type": "range",
                "possible_keys": [
                  "PRIMARY",
                  "pt"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "category_id"
                ],
                "key_length": "3",
                "rows_examined_per_scan": 225,
                "rows_produced_per_join": 225,
                "filtered": "100.00",
                "using_index": true,
                "cost_info": {
                  "read_cost": "24.16",
                  "eval_cost": "22.50",
                  "prefix_cost": "46.66",
                  "data_read_per_join": "3K"
                },
                "used_columns": [
                  "product_id",
                  "category_id"
                ],
                "attached_condition": "(`s2cart`.`products_categories`.`category_id` in (2706,2707,2724,2728,2729,2730,2731,2732,2733,2755,2756,2757,2758,2759,2760,2761,2762,2763,2764,2765,2768,2769,2770,2771,2772,2773,2774,2775,2776,2777,2780,2781,2782,2783,2784,2785,2786,2787,2788,2789,2790,2791,2792,2793,2794,2795,2801,2851,2852,2853,2854,2855,2856,2857,2858,2859,2860,2861,2862,2863,2864,2865,2866,2867,2868,2869,2870,2937,2938,2939,2940,2941,2942,2943,3008,3009,3010,3011,3016,3017,3018,3019,3020,3021,3028,3029,3030,3031,3032,3033,3034,3035,3036,3038,3039,3040,3041,3042,3044,3055,3056,3057,3058,3059,3060,3061,3062,3063,3064,3065,3066,3067,3068,3069,3070,3071,3072,3073,3074,3075,3076,3077,3078,3079,3080,3081,3082,3083,3084,3085,3086,3087,3088,3089,3090,3091,3092,3093,3094,3095,3096,3097,3098,3099,3100,3101,3102,3103,3104,3105,3106,3107,3108,3109,3110,3182,3183,3184,3185,3186,3187,3188,3189,3289,3291,3292,3293,3294,3295,3296,3297,3298,3299,3300,3301,3302,3303,3304,3305,3306,3307,3308,3309,3310,3311,3312,3313,3314,3317,3318,3319,3320,3321,3322,3323,3324,3325,3326,3327,3328,3329,3330,3331,3332,3344,3345,3346,3347,3348,3349,3350,3351,3352,3353,3354,3355,3356,3357,3358,3359,3360,3361,3362,3363,3414))"
              }
            },
            {
              "table": {
                "table_name": "products",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY",
                  "status",
                  "idx_master_product_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "product_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.products_categories.product_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 19,
                "filtered": "8.72",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "1.96",
                  "prefix_cost": "69.16",
                  "data_read_per_join": "150K"
                },
                "used_columns": [
                  "product_id",
                  "product_type",
                  "status",
                  "company_id",
                  "amount",
                  "usergroup_ids",
                  "tracking",
                  "age_verification",
                  "age_limit",
                  "parent_product_id",
                  "master_product_id",
                  "master_product_status",
                  "master_product_offers_count"
                ],
                "attached_condition": "((`s2cart`.`products`.`master_product_id` = 0) and ((`s2cart`.`products`.`usergroup_ids` = '') or (0 <> find_in_set(0,`s2cart`.`products`.`usergroup_ids`)) or (0 <> find_in_set(1,`s2cart`.`products`.`usergroup_ids`))) and (`s2cart`.`products`.`status` = 'A') and (`s2cart`.`products`.`master_product_status` = 'A') and ((`s2cart`.`products`.`company_id` > 0) or <cache>((NULL > 0))) and (`s2cart`.`products`.`product_type` <> 'D'))"
              }
            },
            {
              "table": {
                "table_name": "companies",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "company_id"
                ],
                "key_length": "4",
                "ref": [
                  "s2cart.products.company_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 19,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "1.96",
                  "prefix_cost": "71.12",
                  "data_read_per_join": "182K"
                },
                "used_columns": [
                  "company_id",
                  "status",
                  "company"
                ],
                "attached_condition": "<if>(found_match(companies), ((`s2cart`.`companies`.`status` in ('A','S')) or (`s2cart`.`products`.`company_id` = 0)), true)"
              }
            },
            {
              "table": {
                "table_name": "cscart_categories",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY",
                  "c_status",
                  "p_category_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "category_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.products_categories.category_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 0,
                "filtered": "5.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "73.08",
                  "data_read_per_join": "3K"
                },
                "used_columns": [
                  "category_id",
                  "usergroup_ids",
                  "status",
                  "age_verification",
                  "age_limit",
                  "parent_age_verification",
                  "parent_age_limit",
                  "storefront_id"
                ],
                "attached_condition": "(((`s2cart`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`s2cart`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`s2cart`.`cscart_categories`.`usergroup_ids`))) and (`s2cart`.`cscart_categories`.`status` in ('A','H')) and (`s2cart`.`cscart_categories`.`storefront_id` in (0,3)))"
              }
            },
            {
              "table": {
                "table_name": "descr1",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY",
                  "product_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "product_id",
                  "lang_code"
                ],
                "key_length": "9",
                "ref": [
                  "s2cart.products_categories.product_id",
                  "const"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 0,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "73.18",
                  "data_read_per_join": "7K"
                },
                "used_columns": [
                  "product_id",
                  "lang_code",
                  "product"
                ]
              }
            },
            {
              "table": {
                "table_name": "prices",
                "access_type": "ref",
                "possible_keys": [
                  "usergroup",
                  "product_id",
                  "lower_limit",
                  "usergroup_id"
                ],
                "key": "product_id",
                "used_key_parts": [
                  "product_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.products_categories.product_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 0,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "0.25",
                  "eval_cost": "0.10",
                  "prefix_cost": "73.52",
                  "data_read_per_join": "23"
                },
                "used_columns": [
                  "product_id",
                  "price",
                  "percentage_discount",
                  "lower_limit",
                  "usergroup_id"
                ],
                "attached_condition": "((`s2cart`.`prices`.`lower_limit` = 1) and (`s2cart`.`prices`.`usergroup_id` in (0,0,1)))"
              }
            }
          ],
          "select_list_subqueries": [
            {
              "dependent": true,
              "cacheable": false,
              "query_block": {
                "select_id": 3,
                "message": "no matching row in const table"
              }
            },
            {
              "dependent": true,
              "cacheable": false,
              "query_block": {
                "select_id": 2,
                "cost_info": {
                  "query_cost": "31651.29"
                },
                "table": {
                  "table_name": "cscart_products",
                  "access_type": "ALL",
                  "possible_keys": [
                    "idx_parent_product_id"
                  ],
                  "rows_examined_per_scan": 270845,
                  "rows_produced_per_join": 27084,
                  "filtered": "10.00",
                  "cost_info": {
                    "read_cost": "4566.79",
                    "eval_cost": "2708.45",
                    "prefix_cost": "31651.29",
                    "data_read_per_join": "203M"
                  },
                  "used_columns": [
                    "amount",
                    "parent_product_id"
                  ],
                  "attached_condition": "(`s2cart`.`cscart_products`.`parent_product_id` = `s2cart`.`products`.`product_id`)"
                }
              }
            }
          ]
        }
      }
    }
  }
}