Google "VanitySearch-1.15.4_bitcrack"   and download from GitHub

if your GPU can run  440 Mkey / s  ~~ (Example:  My NVIDIA GTX 1080 )
you will  find  #64 private key about 200 years ....(25% range scan )
you will  find  #64 private key about 400 years ....(50% range scan )

0x0000000000000000000000000000000000000000000000008000000000000000
0x000000000000000000000000000000000000000000000000FFFFFFFFFFFFFFFFFF