Is this in any key?

Borrowing (substituting) chords from outside the key is not "breaking" the rules of Music Theory.

It is "using" them.

In response to noteboat's post... It's completely believable. Not all styles fit together. Not everybody clicks, and no matter what theory books they go by. I wouldnt be able to play a country lick if my life depended on it, so I'd be screwed playing with garth brooks, well, he's an exception...he's closer to rock. The stones have a totally different sound than G3, so it's not surprising. It's all a matter of taste.