If we go by the rules anything above 30Kg is excess thus you will have to pay for that.

Did you try checking on their site??

http://www.airindiaexpress.in/airindiaexpress/Support.asp

Better contact the airline for additional information or guidance on this.

Doha
Reservations: (+974) 4418 423/424
Airport Office: (+974) 4622544

Regards!!