During the call the chain's chief financial officer, Ian Borden, explained just how well that has worked.

"MyMcDonald's Rewards is yet another example of how we've tapped into our marketing engine to deploy our loyalty platform throughout the system," the executive said.

"Now in 50 markets, loyalty is building even stronger relationships with our customers, and the results continue to shine. In our top six markets, digital sales now represent almost 40% of systemwide sales, or nearly $7.5 billion, growth of more than 30% over the last year."

McDonald's' digital-membership numbers are particularly strong when you compare them with Starbucks, the company generally considered the pioneer of app-based loyalty rewards programs and mobile order and pay.

Starbucks, which reports only U.S. loyalty program members, ended its most-recent quarter with more than 30 million active rewards members.

Across its top six markets, McDonald's has an even bigger membership base.

Eoin Treacy's view

Anything that gives consumers the impression they are saving money is going to be a benefit in an inflationary period. The reliability of fast-food revenue and the constancy of dividend growth is supporting their shares.