Hi,
I dont’t know if this is still relavant for you since your topic is more than a year old.
We had the same problem and unfortunately there is no out of the box solution for this (in Keycloak 23.0.4).
You could try to overwrite the TokenManager from Keycloak and a bunch of other classes to compute your own lifespan or see our diskussion here on how we worked around this problem.