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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e4a6836bb93b7dab67c1690b0e83a87495b55da2cdcebffd135cd7fd7e38a85' 
  AND token = 'YJ/g9dqFJQ95eLoZV8ujx+zjDm1oey2F2RD8RUdHDoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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