'Key & Peele' Star -- Wishes Joe Biden Happy B-day ... As Obama

Jordan Peele -- of "Key & Peele" -- has a special message for the veep on his birthday … and he's delivering it perfectly (to our TMZ photog) in his famous Obama impression.

We caught up with Peele at LAX today… and when we informed him that Joe Biden is celebrating the big 71 today ... he immediately channeled the Commander In Chief to offer up some hilarious birthday advice.

Check out the video ... Peele sounds exactly like the prez ... and even drops some 411 on his upcoming movie with Key.