MySQL: How to decrease sleep process's time out?
to check your idle process timeout you can connect to MySQL then execute the following command:

show variables like "%timeout%";


you need to check wait_timeout and interactive_timeout from the results based on those values you can execute the following commands from MySQL to set them:

set global wait_timeout=XXX; -- where XXX equal value less than the original one
set global interactive_timeout=XXX;  -- where XXX equal value less than the original one