Do moving a member and prolongation of lifetime guaranteed in my case

Question

Here is a code snippet:

#include <iostream>
#include <array>

struct Matrix
{
    struct Proxy
    {
        Proxy(Matrix& m) : m_ { m } {}
        Proxy(Proxy&& rhs) : m_ { rhs.m_ }, a { std::move(rhs.a) }, index{rhs.index} {} // 1

        Proxy operator[](int i)
        {
            ++index;

            return { std::move(*this) };
        }

        Proxy& operator=(int value)
        {
            m_.v = value;

            return *this;
        }

        Matrix& m_;
        int     index = 0;

        std::array<int, 1000> a;
    };

    Proxy operator[](int index)
    {
        return { *this };
    }

    int v = -1;
};

int main()
{
    Matrix      m;
    const auto& q = m[1][2][3]; // 2
    std::cout << q.index << std::endl;
    std::cout << q.m_.v << std::endl;
}

I'm interested in behavior of temporary objects in such a case - whether my snippet violates any rules when moving from one temporary to another temporary at point 1 and is it guaranteed that temporary proxy's lifetime will be prolongated at point 2 due binding to const reference?