Q:

How to organize time_stamps with values in lua?

Create something like array of values associated with time_stamps, and getting values by time_stamps. only one value with one time_stamp. How better organise it? And how to remove values after goes  some time?
something like this:
datetime = os.date("!*t",os.time())

array[datetime]=somevalue

And how to delete from that table values older than 10 minutes?

A:

I don't see why using the date table as keys. You can instead use the timestamp directly as keys, something like:
t[os.time()] = somevalue

The timestamps are only integer values, you can get its real date with os.date when in need. 
You can compare them directly. For instance, to remove values that is before May 20, 2014, compare the keys with os.time{year=2014, month=5, day=20, hour=0}.

