I know the 640x480 resolution comes up often. I have been looking for months to be able to take photos at the required size without all the hoops involved with resizing programs and apps.
If you have an Android running KitKat 4.4 or higher search for Google Camera in the Play Store. After downloading, go into Settings, Resolution and Quality, Camera, Back Camera Photo. Once you are there choose the bottom option (4:3) 0.3 megapixels and you will be set to go.