SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '44403ff0a5820120d9abc1d99bd752bf51c15b2924d7193838519c8e60b71e9f' 
  AND token = '2RzBdg3osJX39UdegksM8l+drKpp/WhPiWeMe8/2tpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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