I don't think we can call it real-time below 6 FPS (0.17s). That's the framerate of cheap anime. And the goal should be at least 30, which is a typical video game framerate.

The only examples I have where real-time raytracing is used are demoscene productions where shapes are defined using simple mathematical primitives. (see the 4k intros "absolute territory" and "zetsubo", both from prismbeings for example).