I need sso for some of my other sites and (more importantly) i need to check if my generated token through your backend api is valid through my api gateway. Do guys have and external api in which i can call to check if the token is valid? for example if i want to generate a token using this function https://www.wix.com/code/reference/wix-users-backend.html#generateSessionToken then i send it to my endpoint how do i know it has not expired? when i pass it through my api gateway i need a way to check it in my system. Do you guys have an external api i can call to check this information?