SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53c7df43e2c81bdc1d6699fe29124207729acc29df697e4fd0bce0e38bbb549a' 
  AND token = 'PybAyZ1OJwm1KpmFyrh6dgQDy/VTVdv6j//JIcvLvX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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