ETS select is slow => O(n)

ets select is slow.txt

 https://github.com/sat2707/hlcupdocs/blob/master/TECHNICAL_TASK.md
 
 iex(9)> :ets.info(:visits)
[read_concurrency: true, write_concurrency: false, compressed: false,
 memory: 110008228, owner: #PID<0.3544.0>, heir: :none, name: :visits,
 size: 10000740, node: :nonode@nohost, named_table: true, type: :ordered_set,
 keypos: 1, protection: :public]

iex(11)> fun = :ets.fun2ms(fn {id, user, location, visited_at, mark} when user == 475422 -> id end)
[{{:"$1", :"$2", :"$3", :"$4", :"$5"}, [{:==, :"$2", 475422}], [:"$1"]}]
 
iex(13)> :timer.tc(:ets,:select, [:visits, fun])
{995227,
 [4900032, 4968401, 5719429, 6199945, 6664262, 6840698, 6978489, 7701343,
  9396431, 9659045]}  

995 ms!