Can't get action token {action.unsubscribeUrl} to work in Welcome automated message
I expect the token only gets populated with the relevent URL when it is used as part of a CiviMailing.

The automated message you are referring to does not go out via CiviMail, so it is possible that it will not function in that feature.

Since it seems that the checksum doesn't work directly with civicrm/mailing/subscribe?reset=1 you can set up a Profile that includes your public mailing lists, and send them to that. Bit of a pain having to do the extra steps. 

Using tokens for Profiles is detailed here: https://wiki.civicrm.org/confluence/display/CRMDOC/Tokens

And using Profiles for Mailing Lists is here: https://docs.civicrm.org/user/en/4.7/email/set-up/#allow-people-to-sign-up-for-your-mailing-lists-online