This source says 59 min (in japanese). https://www.athome.co.jp/contents/at-research/vol33/

one in english is here: https://resources.realestate.co.jp/living/average-work-commu...

This one is 45 min ... though that is all of Japan, not Tokyo specific.

btw, I think Tokyo is great. But I think these articles set bad expectations sometimes and I have met a few foreigners that were totally disappointed/burnt out when moving to Tokyo.