Recently I was asked this question in an interview and I could not answer it. Does someone here knows the answer?

There are two closed doors and behind one of the door there lies treasures and the other is empty. These two doors are guarded by two guards. One of them is a liar and the other is a truth teller. You dont know which one of them is a liar and which one the truth teller. You can ask just one question to either of them to know which door has the treasure behind it.

What would be that question?