SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a17fa1510f7170de97b7ef5ccdbb43493962088da5c194214a1f438546868a20' 
  AND token = 'xcwEeOTuu4QqFpkWAe3jdRzTfZlaWapZWMsYTDKpY0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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