Best credit to book flight ticket worth 1L

Scapia

none of those cards are good. APay gives only 5%

If there are multiple flights, book in batches and later select seats nearby

try to get disocunt vouchers, thats the only way for good discounts as far as i know

Axis Flipkart and ClearTrip 4%?

Check au bank offers page, sometimes they run good offers. 

Wherever discount you search, look where there is no or high max discount, it should not be capped like 2500rs otherwise your convenience fee will eat up your discount. 

I would suggest to buy tickets from Google Travel. Fairly cheap. Even more than skyscanner.