SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e794a5b534c0584f81eed2c59d0b7e261e7222f9cfe83187495ffac5cdbf0d7' 
  AND token = '1IYxu1aV707CX6coP+wEe81VJ8xoQGRzdzNiydsW7gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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