It's hard to say what a good time is, since 25y is not a distance used in competitions for anyone but very young kids.
The record USMS time in your age group for 50y butterfly is 24.46 seconds. At a meet I was in earlier this year, 4 men in your age group swam 50y butterfly, and their times were:
So the pace at which you were swimming (if you could have maintained it for 50 yards) would have put you in the same ballpark as the 3rd place swimmer.
But why were you swimming it with only one breath?