Casting integer type on hexadecimal already formatted as string in Java

Question

I have long (32 characters + leading 0x) hexadecimal value stored as string:

String key = '0x000639847445EB1570C9D9C92DAA1FB8'

For this to work, my query should look like this:

Select * from table where key = 0x000639847445EB1570C9D9C92DAA1FB8

It used to work with normal SQL statements but we changed it to Prepared Statement:

setString(preparedStatement, 1, key);

As we have the value in string, this is what it produces:

Select * from table where key = '0x000639847445EB1570C9D9C92DAA1FB8'

and our query does not return anything. Basically, I need to 'extract' the value from string format and apply another type to it without messing up the value, so my final query would have such format:

 Select * from table where key = 0x000639847445EB1570C9D9C92DAA1FB8

I have tried Byte.parseByte, adding this value to BigInt, however nothing seems to give result I'm looking for.