Can not open installed plugins tab

We use Open Journal Systems and recently we faced the problem - it is not possible to open installed plugins tab.
In the error log there is only one PHP Fatal error: Maximum execution time of 30 seconds exceeded in /usr/local/www/hosting/ on line 84, referer:

We have no idea about this problem.
@vitaliy @asmecher

Hi @ActaBiologica,

Can you increase the max execution time for PHP scripts? The setting is in php.ini: max_execution_time
Although, I must say that the script shouldn’t run for so long.