Assuming your machine does not need any feedback from you lubrification pump, you could just put the wires from the coil of your motor contactor and put it in series with a on/off switch. Here I am assuming we're talking about something like a 24Vdc or 120Vac coil for your motor contactor. If it's higher, you should use the NO (could use NC too) connection of another contactor with proper rating with the 120Vac coil (or wtv you have available that is safe to use in a switch), this coil activated/deactivated by an on/off switch. The NO connection would be in series with the connection going to the motor contactor's coil. There are also the high voltage switches that can be bought, though you would be spending your money for nothing. Cheers and don't do this if you don't understand what I am writing about, ask someone qualified!!
-and put your padlock.