Keepalive time out message

Most of the times, I see this message in the event history of my host:
Check_MK - CRIT - [agent] keepalive timed outCRIT, Got no information from host, execution time 120.0 sec

The server is quite busy in the night as it has some nightly backup jobs and other tasks. What can I do in Checkmk to allow it more time ? For example, 150 seconds.

Most of these timeouts happen only during night. Is there a way to give it more time ?