May 2017 security patch is now live for the Galaxy S8 in India.
Samsung has started rolling out the May 1, 2017 security patch to the Galaxy S8 and S8+ in India. The update comes in at 613.25MB, and aside from the May security patch, there doesn't seem to be anything else that's new (at least from a user-facing standpoint).
The changelog details the usual stability fixes, "enhanced features", and performance improvements. The build increments the version number to G950FXXU1AQE5 on the Galaxy S8 and G955FXXU1AQE5 on the S8+.
If you're using either phone in India and don't see the OTA update yet, head to Settings > Software update >Download updates manually to initiate the download. As the update is over 600MB in size, make sure you're on a Wi-Fi network before starting the download.