The explosion-proof specification will be “Specifications that have taken special technical measures so that it will not be an ignition source of combustibles”.
Unlike an endoscope with a built-in camera at the tip, the borescope is made up only lens and fiber. There is no electric thing at all.
(The borescope itself is not an ignition source.)
Of course, dedicated equipment is required for light source devices and cameras in environments where explosion-proof is required.
For example, it seems that the following explosion-proof C-mount camera are on sale.