If I execute
php -i | grep "openssl" then I get OpenSSL support => disabled (install ext/openssl)
even though I uncommented the line
extension=openssl in the loaded configuration file (php.ini).
I found the php.ini by executing
php -i | grep -i "loaded configuration file"
Loaded Configuration File => /usr/local/lib64/php.ini.
I even restartet the webserver, even though this is not necessary for PHP CLI.