Looking for very fast fixed length string search algorithm in a fixed length string database

I would appreciate suggestions for very very fast algorithm that determine if an 8 bytes string is NOT present in a database of strings where each string is also 8 bytes in length. There are a couple of hundred millions of strings in the database. There may be clusters of strings in the database. I am thinking of using the Aho Corasick algorithm, but I hopethat there may be faster technique.

Many thanks for your help.