I have tested the Logitech K400 Plus TV keyboard with the Sony Bravia XBR49X800D, and it works flawlessly. Simply plug the USB dongle into the TV, it is truly plug-and-play, no drivers are required to install. Go into the TV settings and select “physical keyboard” and then the keyboard language, and you are ready to go. All of the buttons map correctly as of the latest firmware updates in November 2017 with Android 7.0. The keyboard has arrow keys and a touch pad as well, all working. The shortcut keys along the top of the keyboard are all correctly mapped and work, for such functions as back, home, volume, etc.
If you buy this keyboard and have difficulty finding the USB dongle in the box, see my previous post, it is probably located in the box but hidden.