SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2456701edb495575bd75385b77250d5836d0de07689a3b86bd165c07e6ff3b10' 
  AND token = 'IUVrxgyUs87hEbenkOZfYHfuHWZd8tsDugUAhfmPRns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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