The ON semiconductor 2N2222 datasheet shows only ~0.1volt saturation voltage with 100mA LED current and that base current. Not worth changing to a mosfet.
Too much base current makes switching the transistor off slower.
Google "Baker clamp" for more info.
For a single IR LED, an emitter follower is another option.
Base directly to the Arduino pin, collector to 5volt, and LED/CL resistor between emitter and ground.
Saves one resistor. Has 0.7volt drop, so calculate CL resistor accordingly.
Leo..