God, this shit makes me laugh. Why are they doing this.

But from Edit2: Your hash is some sort of base64

     let str = 

"ME4wTKADAgEAMEUwQzBBMAkGBSsOAwIaBQAEFDOB0e_baLCFIU0u76+MSmlkPCpsBBRXF+2iz9x8mKEQ4Py+hy0s8uMXVAIIfYbtkeEKZsI="

Then we see weird random gaps in the alphabet used, not so weird, because not every character will be used in every string:

     Prelude Data.List> map head $  group $ sort $ str
     "+0246789=ABCDEFGIKLMOPQRSTUVXYZ_abefghiklmpstuwxyz"

If we fill these up then:

      Prelude Data.List> let xs = "+0123456789=ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"
      Prelude Data.List> length xs
      65

So base64 with some non standard symbols. I don't know what standard base64 is supposed to look to be honest, so perhaps it is standard base64. The = is definitely padding.