SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac679453968df6c07f452e5dcf9db1b90e493563ce0571f80ff79a3e948dae7c' 
  AND token = 'U81CBXnQGhiWBzxwbYyTZVY68YMki4rYHcU+lEGHbA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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