Another method would be to use a line trace from the character’s view (if first person) or the character’s face (if third person). You can set the keybinding to run a line trace everytime it’s pressed. If the line trace hits the door, which you can determine by casting to the door’s blueprint class, then it calls an event on the door to cause it to open.
You can find more about line traces here:
https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/UseRaycasts/Blueprints/index.html