Can a relay be used for higher voltage lesser current than the rated voltage and current?
No, and especially not if you plan to use this in a product. There are several reasons for this: 
The contacts will arc and the relay will not shut off when open. There are creepage and clearance distances, going over the rating will make it impossible to clear regulatory. Another problem involves the contacts, they are designed to maintain a certain contact resistance, if the voltage is exceeded you could get welding to the contacts at worst case or a degradation of the contacts.

If this is just for a hobbyist\prototyping application, your welcome to try it YMMV and your relay could go up in smoke as well as burn up your input.