var craftingRecipeWithTime = craftingRecipe as CraftingRecipeWithTime;
if(craftingRecipeWithTime == null){
Debug.LogWarning("CraftingRecipe is not a crafting recipe with time");
return;
}
var craftTime = craftingRecipeWithTime.CraftTime;
That's assuming you do have a public getter for craft time.
The null check is to make sure you don't have a recipe with another type.