SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd523967256bc83a04d8affb8817706fd0382e2280f18b1d8282c23637f30ed6' 
  AND token = 'y21THdEdWyLhFgPGz0ERsVIeoIgmlIqiXJczLED0WpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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