This article covers checking the cron log to verify if a specific cronjob was executed.
Cron logs are stored at /var/log/cron. You'll want to search this log for the user that owns the cronjob. For example:
-bash-4.2# grep cptest /var/log/cron
Aug 8 03:45:01 cent7 CROND: (cptest) CMD (/usr/local/bin/php /home/cptest/public_html/cron.php)
From the above we can see that "/usr/local/bin/php /home/cptest/public_html/cron.php" was executed at 03:45 AM on August 8th.