If you want to perform an AutoSSL check on a single user, you may do so by making use of the following cPanel provided script:
[root@the ~]$ /usr/local/cpanel/bin/autossl_check --help
autossl_check ( --user=<username> | --all | --help )
This command will do a single AutoSSL check of either all users or a
To check a specific user simply use the appropriate flag and AutoSSL will limit its run to the domains owned by this user.
[root@the ~]$ /usr/local/cpanel/bin/autossl_check --user=$USER
Additionally, this script will also provide you with the logs of the domains that it has checked; this can be very useful to be able to quickly identify problems that any of your domains may encounter when attempting to obtain a certificate.