Are there any photorealistic paintings that date back to ancient times?
This question depends entirely on your definition of photorealistic. There are accounts of certain Ancient Greek and Roman painters who were so skilled that they often tricked individuals into thinking they were looking through a window rather than at a painting, such as Thales and Cydias, but no works from this period survive for us to be certain.
Paintings that do survive do show an impressive talent for dimensions and perspective, but not to the extend of the Renaissance and modern period. The skill of ancient painters can be reflected in the Ancient Greek and Roman sculpture of the time which was extremely realistic in its portrayals and dimensions.