In case I missed a country when I set the restrictions, here's the list:

Region Lock Warning
This key is not available in the countries listed below. If the gift recipient is located in one of these countries, they may not be able to redeem the key.
AM Armenia, AR Argentina, AZ Azerbaijan, BO Bolivia (Plurinational State of), BR Brazil, BS Bahamas, BY Belarus, BZ Belize, CL Chile, CN China, CO Colombia, CR Costa Rica, EC Ecuador, GE Georgia, GF French Guiana, GT Guatemala, GY Guyana, HN Honduras, KG Kyrgyzstan, KR Korea, Republic of, KZ Kazakhstan, MD Moldova, Republic of, NI Nicaragua, PA Panama, PE Peru, PY Paraguay, RU Russian Federation, SR Suriname, SV El Salvador, TJ Tajikistan, TM Turkmenistan, UA Ukraine, UY Uruguay, UZ Uzbekistan, VE Venezuela (Bolivarian Republic of)