The closest you can physically get would be Bangalore, from where it's a 1hr55 Air India flight to MLE. I wouldn't really recommend it though as a transit unless a stopover in India is appealing to you. We actually did this before BA flew to MLE: a few days in Delhi, and then we had to connect through CMB to MLE back then. In fact we overnighted in CMB which had the advantage of us getting to MLE early.
I mention this in case: have you noticed that BA has just launched lights to SEY. The Seychelles are great but not the Maldives - there are honeymoon resorts but they're quite different. So if you've understandably set your heart on MLE I wouldn't change it, but SEY would be a more practical choice!