It is more than likely a computer print. Using a spray on it could be a major disaster, or not. Best bet is to try and get a duplicate before trying a spray, or at least know that a duplicate is available.
It also may be possible to go to a printer and have it scanned and printed. Whatever, do not spray it until you have checked all the alternatives.
Some computer prints take sprays just fine, others don't. If you end up trying a spray, use Krylon mat finish spray. Do NOT use photo dulling spray. Photo dulling spray is not intended to coat photos, it is intended as a temporary dulling agent for shiny surfaces that are going to be photographed.
John