Either one.
When you think of a "chunk" of time, you can use the singular: Ten years is a long time. Fifteen minutes is long enough to wait.
(It's the same with distance or money: Two miles is too far to walk. A hundred pounds is not too high a price.)
In this case, though, it almost feels as though you are counting the minutes, so that the ten minutes are ten separate minutes, not a chunk of time.