Where in a MySQL statement can I use pyformat variables/parameters?

Here's an example that doesn't work:

stmt = '''
    SELECT `date_new`, `event`
    FROM `events`
    WHERE `date_new` > TIMESTAMP(DATE_SUB(NOW(), INTERVAL %(days)s day))
'''

args = {'days': 30}

c.execute(stmt, args)

which gives me an error: ValueError: Could not process parameters.

A query that includes something like this:

WHERE quantity = %(qty)s

works just fine.

I did find this: What parts of a SQL query are allowed to be parameterized? But that leaves the question in the specific example above: What about the argument to INTERVAL makes it not work?

I have found lots of documentation about the basics of using pyformat variables/parameters. I think part of the problem I'm having finding something is that it involves the intersection of Python and MySQL via mysql.connector.

I'd like a pointer to some documentation about what parts of queries allow their use and what ones don't, specifically for MySQL.