0 second animations are still 1 second

I have animation with just 1 keyframe.
I have set all the transitions to 0, being instant.
Inspector shows that animation is 0 seconds long.
Time scale is 1.
But since it only has 1 keyframe, unity keeps the default animation length, which is 1 second. So any animation I want to be instant, is 1 second.
Hack is to set the playback speed to insanely large number like 1e+30, but that just seems stupid for something that should work.

Any better ideas how to solve this issue?

 

Some workaround would be to make two keyframes very close to eachother (close to 0 time)