Declare a function noexcept which can theoretically throw but not practically

Is it safe to declare the following function noexcept even though v.at(idx) could theoretically throw a out_of_range exception, but practically not due to the bounds check?

int get_value_or_default(const std::vector<int>& v, size_t idx) noexcept {
    if (idx >= v.size()) {
        return -1;
    }
    return v.at(idx);
}