SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '683078d415e8b6a105c9c76eb1f1104f51e2505ebf8220e94625904ce7cb616b' 
  AND token = 'BU9JiZhwzSCz7w+gLa/+B/Qmgn6NCNoHZTJDsgWkfLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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