It is not 64 bits its 256 bits or 32 bytes (52 characters in text). And the answer is no you can't use a truncation of the key to lookup the node, unless you;

1) use an indexer that offers this translation from the truncated key to the full key.

2) the truncation has to be large enough to avoid someone creating another key with the same short prefix and now no one knows which is the key that the user wanted.

So let's say your truncated key is made of the first 10 characters... It wouldn't take long for me to find a key with the same first 10 characters and now I can pretend to be you.

It is best to just use the full keys and let the software locally handle the pet names, like your phone contacts where you are never writing people's phone numbers, you just start writing their name and your phone is giving you the suggestions you are looking for.