SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c956d05604546bf6a2bf15fc544ea394f983669cb47c8dc8cb58d8a16c7dbade' 
  AND token = '//Qs9BVVwZ28srnmrvJSKV31MNG79QQFDlprVZXzcMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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