In a medium bowl, whisk together lemon juice, maple syrup, mustard, oil and salt until smooth. Transfer to a gallon-size resealable bag. Add chicken. Seal bag, pressing out excess air. Gently toss to coat chicken. Place on a large plate and refrigerate 1 to 4 hours.
Preheat oven to 425 degrees F. Line a rimmed baking sheet with foil and coat foil with cooking spray. Place chicken on baking sheet, leaving behind excess marinade. Bake 20 minutes, until drumsticks are cooked through.
Tip: For crispier skin, broil 1 to 2 minutes after chicken is cooked through.