definitely not...MP0 will never see keys drop (well, rarely, 5% chance).
MP4 is perfect for finding keys and 1-2 deads an hour isn't bad at all. That's about what I was doing and I could average about 1.5 keys an hour give or take. If you can bump it to MP5 with maybe 1-2 more deaths an hour...you're in good shape. In this case, a few extra deaths is expected...though you shouldn't be getting any more than 5-6/hr. I typically averaged 2-4 deaths an hour on MP5/6 (went to 6 with my monk and the weapon swap).