Is there a way to only include certain matching conditions
in indexes?

Example if I have a row I want to index that is mysql dates
(2007-06-07) and I only want to include CURRENT and FUTURE
dates in the index and ignore any past dates. Is that
possible at all?

The issue I have is that the ratio of queries on old vs.
new data is like 1:100000. And searches would be MUCH
faster if I could force my queries that are looking at
current or future data to use an index that ONLY had that
information in them..

Thanks in advance for insight here.