Log information to find out N1QL query timeout

Can anyone tell me how to figure out /debug logs when a N1QL query timeout has happened.
I could get the http status code from http_access.log when the N1QL query is executed from the Couchbase UI.
But when the same query is being run using curl command or using cbq command line tool I am unable to find the information on where it gets logged.
Is there any flag count or statistic variable that indiactes a N1QL query timeout has happened?

In 4.5 / 5.0 your best bet it the completed_requests system:keyspace, if the timeout is set to higher than the completed requests threshold.
You will find the information about the request that times out if you select from system:completed_requests, alongside with status, execution times, etc.