base64 decode a mysql column before performing a WHERE

Basically - its a long story - but I have a field in a database that is encoded as a base64 string.

EG: this is stored in the database:

YToyOntzOjIwOiJUeXBlX29mX29yZ2FuaXNhdGlvbiI7czoyMDoiTWVtYmVyIG9mIFBhcmxpYW1lbnQiO3M6ODoiUG9zdGNvZGUiO3M6NzoiUEUxIDFKQSI7fQ==

Which equals this:

a:2:{s:20:"Type_of_organisation";s:20:"Member of Parliament";s:8:"Postcode";s:7:"#postcode#";}

What I want to be able to do is select where this string LIKE '%Member of Parliament%'. Is there any way to base64 decode a mysql column before performing a WHERE?

eg: SELECT * FROM table WHERE base64_decode(column) LIKE '%Member of Parliament%'

Thanks