Strugglers Carlisle crashed to their sixth home defeat of the season in what was little more than a walk-in-the-park for Scunthorpe, beaten only twice on their travels this season.
Keegan is on loan for a month to help them out with injuries and suspensions. But there was little evidence of that and one of the goals came from ex-Leeds defender Kevin Sharp.
His angled volley from 25-yards was a superb effort as it flew in at the far post just past the hour mark.