I also got my way after trying some things out and it is actually pretty nice.
First, I have 1 object for each player which I just call "controlls" or smth like that. In the event sheet I code it like that:
While D down -> set controlls "right" to 1
Else -> set controlls "right" to 0
And then if right is equal to 1, simulate movement right
This way I can always change key-bindings pretty fast or add something like touch support and AI behavior without problems.
The "controlls" object is just somewhere out of the window and is not visible ingame.