Yep, if you typed this command literally you would indeed get an error.
For the first half ( /usr/php/54/usr/bin/php ), this has to be the location of your php in use by moodle. Find this by going to Site Administration, Server, php Info. Look at the "Loaded Configuration File" entry.
For the second half (/home1/domainfolder/public_html/admin/cli/cron.php) I would SSH into my server, cd to my moodle folder (or even all the way down to cron.php), and then type "pwd". This would show me the entire path to my moodle.