Coronavirus is an enveloped virus, thus it is not as robust as naked viruses and won't survive a dry environment for as long. The longest estimates i've seen is ~5 days, but most enveloped viruses survive and remain infective less than that. Furthermore, coronavirus is respiratory, so to become infected you would need to inhale droplets containing virus. All told, if the case's surface is contaminated, the virus will be gone by the time it reaches you, more so if there is a dessicant added to the box as is often the case. Second, wash your hands. Third, don't lick your case, I guess.