It looks like the php-mcrypt version in your yum library is for PHP 5.3.3.
Your PHP version is 5.4.23. Try this: http://rpms.southbridge.ru/rhel6/php-5.4/x86_64/php-mcrypt-5.4.23-1.el6.remi.x86_64.rpm
Download the RPM from above and run rpm -ivh <name>
Make sure you have libmcrypt installed separately though. Yum installs all dependencies, so if you were using yum it would've installed libmcrypt