SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '987ca70ff65e0cafe8467e11310195768689f62d7480ba857f1659fadb148b56' 
  AND token = 'dav76dsvlKRH1AqWCd/Rn3VGjnvt3VIvXYDoBHcIRGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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