Custom query with Squeel on equality of two attributes to ordered pairs

Question

I'm having difficulty writing a query, whether in SQL or not, but I'd like to be able to write it in ruby using the gem Squeel. Basically, I have a class:

class Article < ActiveRecord::Base
  belongs_to :genre
  belongs_to :publisher

  ...
end

I want a scope that takes in an array of ordered pairs of the format (genre_id, publisher_id) and outputs an ActiveRecord::Relation that contains all of the records with genre, publisher pairs equal to the pairs passed in.

Basically, I want Article.where{ genre_id.eq_any [1, 5, 76] }, except instead of a single attribute, I want it on a pair of attributes:

Article.where{ genre_id_publisher_id.eq_any [(1,2), (1,4), (2, 4)] }

The only way I can think of doing it is making a scope with a select call that adds a column which would be the concatenation of the two ids with some delimiter, then searching based on that:

Article.select(*, 
  "#{genre_id}-#{publisher_id}" as genre_publisher_pair).where(
        genre_publisher_pair.eq_any ["1-2", "1-4", "2-4"])

However, that seems like too much overhead. I also already have a compound index on [genre_id, publisher_id] and I'm afraid this won't use that index, which is going to be a requirement for me.

Is there an easier way to write these compound scopes? Thanks!