SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afdfc3653a14abeba5944b66f9a781f1942056c0da16ae71a45050f959794439' 
  AND token = 'lrDIzjz5DkgQmDKhFIHttdPzXPyrKm+hd00j3Mq+OA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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