Food prices include several costs. Since humans rarely directly consume corn or soybeans, this answer refers to processed food products.
Food prices are affected by increases in corn or soybean prices, but also by other costs, such as wages and transportation. For example, foods that have to be shipped or hauled long distances will be affected when the cost of fuel rises.
GM crops have increased the supply of corn and soybeans so the rise in food prices is lower than the case if GM crops did not exist. Research conducted by Graham Brookes indicates that corn-based products would be priced 6% higher and soybean-based products would be 10% higher if GM crops were not grown. The increased supply of these crops lowers the price that farmers receive for growing these crops and some of these savings are passed on to consumers, through lower food prices or through smaller increases in food prices.
GM crops are part of the solution to food shortages, not the answer. Many countries that experience food shortages are also affected by war and incomplete road networks, making the distribution of food very challenging. The fact that more food can be produced is of little value when a war prevents that food from being distributed to those in need.