In a large bowl with an electric mixer (or in the bowl of a standing mixer fitted with a paddle attachment), beat butter and sugar until light and fluffy. Add salt, curry powder, cumin, black pepper, turmeric, and cayenne. Beat until well combined. Scrape down mixer and sides of bowl. Beat in flour until well combined.
Turn dough out onto a large piece of waxed paper on a flat surface. Using a lightly floured rolling pin, roll dough into a 2-in.-wide log about 12 in. long. Wrap in waxed paper and chill until firm, at least 1 hour and up to 2 days.
Preheat oven to 325° and set oven rack in middle position. Cut dough into 1/4-in.-thick slices. Lay slices at least 1/2 in. apart on baking sheets. Bake in batches on middle rack until set but not brown, about 12 minutes. Cool on wire racks.
Note: Nutritional analysis is per cracker.