Car has 167,000 miles and, at a traffic light, it stalls.
Well then, time to take it in and get it fixed. A Prius probably needs a dealership service department. Very odd the CEL nor any other warning lights illuminate.
Could be a dirty throttle body. You didn’t mention the check engine light. Is @Purebred correct that it’s not coming on?
If the engine restarts when pressing the accelerator then this is normal.