ConsumeKafka keeps a pool of consumers behind the scenes, equal to the number of concurrent tasks for that instance. So in a simple case with ConsumeKafka having 1 concurrent task, the first time it executes it will ask the pool for a consumer, there will be none the firs time through so it will create a new one, consume the data from Kafka and then stick it back in the pool for next time.
From reading Kafka's documentation (https://kafka.apache.org/documentation) I would expect that the session timeout and heartbeat apply to the consumer while it is sitting the pool. So with the above configuration you described, I think the consumer in the pool would send heartbeats and stay active for 5 mins, then when the processor executed 5 mins later, it would have to create a new consumer from scratch.