I’ll bet the Soviets got a few with the MiG-31, but if they did, they wouldn’t release that to the public.

The Soviet PVO have claimed they did the MiG-31s were flying at Mach 2.35. Whether they would be able to take out an SR-71 in a real shoot-down attempt is unlikely.

I read the USAF stopped flying over Soviet territory when the MiG-31 entered service (Sled Driver).

The USAF never tried to fly over Soviet territory with the SR-71, the aircraft was designed not to fly over other countrys’ territory but fly parallel to their borders and coastlines and make their observations from there.