For future reference if someone else has the same problem.
Found out that the high availability of the database cluster was causing this. For some weird reason another server was sending old data back to the mysql server on which this wordpress site is connected at the moment.
The strange thing is that it was only the cron row in wp_options that was affected with this, but the important part is that the cause has been found.
The cause was not wordpress related itself, but still only affecting wordpress for some reason…