SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198e25dd84fb2c528833b671e52982ebff9edd3b74baeace293d8d349d33fa79' 
  AND token = '9AV8n52opFjA7LgIahRGxg3bnMUxPuHQPaPzdWJn+vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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