Yes , you can order a single (1) box of contact lenses. You can select the quantity for the right eye and then select quantity 0 for the left eye.
If your prescription is the same for both eyes then you can wear the lenses in both eyes accordingly. It is not like buying a pair of shoes where the left shoe and right shoe have a different fit . if the power is the same e.g. -2.00 for both right and left eyes, then you can buy a single box on the right eye and use the lenses within it for both your left and right eye,
Having said this , it is recommended that once you use a lens in your right eye, that you always and only use that lens in that eye and that you do not interchange, This is to prevent the possible spread of infection should that arise.