Re: CPU Consuming query. Sequential scan despite indexing.

I didn't look deeply but it sounds like you are looking backwards into 60 days worth of detail every single time you perform the query and computing an aggregate directly from the detail.  Stop doing that.  By way of example, at the end of every day compute the aggregates on the relevant dimensions and save them.  Then query the saved aggregates from previous days and add them to the computed aggregate from the current day's detail.

David J.