Bit(map) matching in hardware
I'm assuming you want to do this in hardware, rather than software, because of the tags you selected.

I suspect that the fastest implementation would be to use a 64-to-1 multiplexer with X as the select input. The output of the multiplexer is the bit value you want to check. No additional logic is needed...if the mux output is 1 then the bit you want to check is 1, and vice versa.

The actual implementation of the mux itself may depend on how you intend to build the thing. In CMOS VLSI it might be best to use six levels of 2:1 multiplexers. In an FPGA just write the Verilog and let the tools do the heavy lifting.