What is the proper way to perform a contextual search against NoSQL key-value pairs?

Question

With MySQL, I might search through a table "photos" looking for matching titles as follows:

SELECT *
FROM photos
WHERE title LIKE '[string]%';

If the field "title" is indexed, this would perform rather efficiently. I might even set a FULLTEXT index on the title field to perform substring matching.

What is a good strategy for performing a similar search against a NoSQL table of photos, like Amazon's DynamoDB, in the format:

{key} -> photo_id, {value} -> {photo_id = 2332532532235, title = 'this is a title'}

I suppose one way would be to search the contents of each entry's value and return matches. But this seems pretty inefficient, especially when the data set gets very large.

Thanks in advance.