If you want to see how long your database queries actually take, you need to disable MySQL's query cache. This can be done globally by logging into a database console, run

SET GLOBAL query_cache_type=OFF;

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and restart your rails server.

You can also disable the cache on a per query basis by saying

SELECT SQL_NO_CACHE * FROM ...

You also probably want to disable Rails internal (per-request) cache. For this, wrap your code with a call to ActiveRecord::Base.uncached. For example, as an around_filter:

def disable_cache
  ActiveRecord::Base.uncached do
    yield
  end
  true
end

Don't forget to re-enable MySQL query caching later with

SET GLOBAL query_cache_type=ON;