Can I import FBX with constant (step) interpolation?

I created an animation in Blender and made sure all keyframes used “Constant” interpolation (AKA “step” interpolation or “no” interpolation). I’m animating only Shape Keys (AKA Blend Shapes). The animation is 24 fps.
I then exported the animation to FBX and imported it into Unity. When I play back the action (which plays at 60 fps, I’m assuming), I noticed that the keyframes are not actually constant, but there’s a quick linear interpolation from one 24fps frame to the next. This probably wouldn’t be a problem if the frame rates matched, but because I’m going from 24 to 60, I can see the interpolation on one or two frames. There are a lot of keyframes so this is very noticeable. [|160126]

In Unity, is there a way to set the keyframe interpolation mode to Constant/Step for a single object? Preferably without code.

We also ran into this problem…

Seems like this is a known issue: