Yes, both tense forms can be used with as if/as though, just like with if - for both real and uneal situations. Compare:Ahmed is looking hard at him as if he knew him. ( He doesn't.)
It looks as though it's going to rain. - a real situation: there are obvious signs of the coming rain.
He is looking at me as though he was going to kill me. - unreal situation (hopefully).
That's how I see it.