SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a672668f2946f1572aba6571235603597761ed1c7439e6f233a8c5bb94934d6a' 
  AND token = 'ZDDV+tbmIJw1sRaJ5Lt/d0ykrRFt6wVEFYtWzvhVXqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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