CONFIG_IRQ_KEY is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin

IRQ KEY

configname: CONFIG_IRQ_KEY

Linux Kernel Configuration
└─>BF548 Specific Configuration
└─>Priority
└─>IRQ KEY
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
depends
CONFIG_BF54x