I seem to recall that while the Mig-25 Foxbat go awfully fast, engine life at it's higher speeds was very, very short. I seem to recall 25 hours and less.
Are there any still flying? They have been retired from military use (so far as we know), but I knew a few examples were still being flown for research purposes. I'll bet these have been retired too. After the SR-71, what is the next fastest plane? Can any other plane cruise at more than Mach...