Function parser_expr_to_scalar_value_literal_at 

pub fn parser_expr_to_scalar_value_literal_at(
    expr: Expr,
    require_now_expr: bool,
    scheduled_time: Option<DateTime<Utc>>,
) -> Result<ScalarValue>

Same as parser_expr_to_scalar_value_literal but uses the provided scheduled_time for evaluating now(). If scheduled_time is Some, now() will be simplified to the given timestamp instead of the current wall-clock time.