Hi pacman94,
actually, the ( correct / recommended! ) nginx directive:
	
		Code:
	
	
		    if (!-e $request_filename){
        rewrite ^(.*)$ /index.php break;
        }
	 
 OR
	
	
	
		Code:
	
	
		    if (!-e $request_filename) {
        rewrite ^/(.*)$ /index.php?q=$1 last;
        }
	 
 
... are the basic 
rewrite directives, which should work in most cases. If you desire to learn more about NGINX directives, I recommend the official NGINX documentation at:
( Pls. keep in mind, that Plesk already uses ( standart ) location directives within the ( standart ) domain specific nginx configuration files, so that additional directives might conflict with already existing location directives. A location directive can only be used ONCE, so that "if" - statements can be used to add additional directives, without conflicting with earlier settings/configurations. 

 ).