Is spray paint safe indoors?
No. Spray paint is not safe to use indoors. You need to read the label. Generally, the label contains a warning that it should only be used in a well ventilated area.
Yes! But be mindful of the fumes. They are high in VOC (Volatile Organic Compounds) These compounds are bad for the environment and your health. If the box is going to be indoors allow it to fully dry outside. the scent cant be really overwhelming if you have it indoors too soon. Why not try painting it with ZERO VOC paint? Or is your mind set on using spray paint?
I would try the Best Cleaner Ever from ScraPerfect. It is effective and safe--for people and the environment. It removes spray paint and other kinds of paint and yet it has no fumes and is safe for skin. (It also removes adhesive and sharpie markers...) You can google it--there are lots of videos about it also.