SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7263798eaac2bcda3503868dd61a01263e4fabc7fcba7556e536a6259cafa00c' 
  AND token = 'N0lxWREc+MOBZlHoVhdmCIsiA7Oi5Q23N/6QPNiSmlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}