Check if a Moodle user is online

I need to know if a user is on-line at Moodle, there is a [Moodle block][1] for it, but actually it just check if the user had an activity on Moodle in the last X minutes, but in my case that is not useful. There is anyway to know it? [1]: https://docs.moodle.org/24/en/Online_users_block