Thank you Prasad for your inputs.
We did the query performance analysis already using mongo shell and it is optmized already.
The real problem we are facing or suspecting is, since Mongo template is forcing the date to EPOCH this might be slowing down the response time. In Mongo shell the same query uses ISODate and response time is very good as i mentioned in my original post
We tried using simipleDate format but still the final query (in debug inspect) we can see EPOCH date. Is there any option to force it it use ISODate?