After restarting httpd (service httpd restart) I get the following error:
Stopping httpd: [ OK ]
Starting httpd: httpd.worker: Syntax error on line 222 of /etc/httpd/conf/httpd.conf: Syntax error on line 9 of /etc/httpd/conf.d/php.conf: Cannot load /etc/httpd/modules/libphp5-zts.so into server: /etc/httpd/modules/libphp5-zts.so: cannot open shared object file: No such file or directory
You might need to install php-zts though.
yum install php-zts
After that no more error messages and httpd is starting normally with module worker active.