Can I use a stock photo as a background for a 3d NFT?

If I understand correctly, you're selling the 3D object and not the rendered image? Then it's OK. If you are selling a 3D render of an object of your creation, on a table image licensed from stock, I think that in this case you are still OK, as long as the 3D object is clearly the main incentive to buy the composed image.

Look here for more information on licensing: https://community.adobe.com/t5/stock/links-for-licensing-terms/td-p/11366788
(Disclaimer: As always with licensing, this is my interpretation of the rules. I think they are correct and advice is based on reading and interpreting the licence terms and on fair use for both the buyer and the artist/stock company, but I cannot rule out that my interpretation is wrong. I'm not an Adobe employee).