I'm using http keep-alive on the apache server,
Allows say I request it to help keep the connections open up to 2 minutes...
Now, when the connection is produced and idle for any minute, will the assets held by php,
like mysql connections, file handles, etc., is going to be freed or can they survive too ?

Confirmed. Keep-Alive is really a mechanism to avoid pricey TCP connection settlement. Your PHP process/thread begins normally and requires to allocate all assets as always.

Regarding a higher load situation, it may be smart to even keep your keep-alive period much less high: All connection demands compete free of charge connection slots of the server. If all slots have been in-use by keep-alive connections, other customers may not connect.

But, as always, the perfect quantity of slots and good keep-alive period is dependent in your specific load situation.

no , http keep-alive save assets of tcp connection . php and mysql won't even conscious of that connection is open , when you'll make next request it might be fast because time spend solving ip , and opening new tcp connection is going to be saved all of this things remain with apache.