Is there a way to resize the image without pixelation?

[nopropsgames]

(Just for clarification, i am using Gimp 2.8)

I had a similar problem with another image (the image size was 777 x 777) however, this is much different,

I took a picture of a old metal key i had lying around, and made the background (mostly) transparent (still leaving a shadow) however, i had to scale this down to the appropriate size for my game, but when i did that, it became all pixelated, (and i would like to maintain the same look of the image, despite the size.

Any help would be greatly appreciated,

Thanks in advance,

- nopropsgames