The 24-year-old, born in Corby, has played twice for the U21s in 2009/10 but has yet to represent his country at full international level.
McKay, who has scored six goals in 15 appearances for his club side this season, received the call-up by Northern Ireland boss Michael O'Neill after Derby forward Jamie Ward was forced to withdraw from the 24-man squad with a hamstring injury.
The Northern Irish lie fourth in World Cup Qualifying Group F on two points, one place and one point above Azerbaijan.
Kyle Lafferty is likely to lead the line in Belfast, potentially with Dean Shiels in a supporting role, with David Healy and Will Grigg set to be named among the substitutes.
But, with six goals to his name in 15 appearances this season, McKay has one more goal to his name this season than the latter pair combined.
Northern Ireland got their Group F campaign back on track last month with a 1-1 draw against Portugal in Porto and will be looking for their first win under O'Neill.