Unreal Engine 4.25
- Right click the animation track (the space between the keys), and in Properties, unlock the Section range Start and Section Range End properties to make the section time finite so it can be scaled.
* You can also set custom start and end time for the section.
The Track (the green range) will now be finite, containing the keys.
- Ctrl + Drag the end of the track to scale it including the keys.