Any person who sells at retail any potable spirituous liquor product labeled as whiskey, including blended whiskey and blends of straight whiskeys, except products containing 20 or more percent of straight whiskey or whiskeys which have been aged in charred oak containers for three or more years after distillation and before bottling is guilty of a misdemeanor, except that this section does not prohibit the sale at retail of unaged corn whiskey, when so labeled, or the sale at retail of gins, brandies, rums, cordials, liqueurs, bitters, or other distilled liquor products, or products compounded of distilled spirits and other materials, when in no wise labeled as whiskey or blended whiskey or blends of straight whiskeys, or the sale at retail of Scotch whiskeys, or spirit whiskeys containing not less than 5 percent straight whiskey, three years old or older.