Pour the chickpeas into a large bowl. In a small skillet, heat the peanut oil until shimmering. Add the mustard seeds, partially cover the skillet and cook over moderately high heat until the mustard seeds stop popping, about 1 minute. Add the cumin and fennel seeds and the crushed red pepper and cook until the mixture is fragrant, about 30 seconds. Pour the hot oil and spices over the chickpeas. Stir in the yogurt, lemon juice, sliced scallions, chopped cilantro, and mint and salt. Serve the chickpea salad at room temperature.