SELECT 
  sess_id 
FROM 
  cscart_stat_sessions 
WHERE 
  uniq_code = 1123279416 
  AND timestamp > 1732207374 
  AND cscart_stat_sessions.company_id = 1

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "223.61"
    },
    "table": {
      "table_name": "cscart_stat_sessions",
      "access_type": "range",
      "possible_keys": [
        "timestamp",
        "company_id"
      ],
      "key": "timestamp",
      "used_key_parts": [
        "timestamp"
      ],
      "key_length": "4",
      "rows_examined_per_scan": 159,
      "rows_produced_per_join": 7,
      "filtered": "5.00",
      "index_condition": "(`eshopuga_upgr_4122`.`cscart_stat_sessions`.`timestamp` > 1732207374)",
      "cost_info": {
        "read_cost": "222.02",
        "eval_cost": "1.59",
        "prefix_cost": "223.61",
        "data_read_per_join": "13K"
      },
      "used_columns": [
        "sess_id",
        "uniq_code",
        "timestamp",
        "company_id"
      ],
      "attached_condition": "((`eshopuga_upgr_4122`.`cscart_stat_sessions`.`company_id` = 1) and (`eshopuga_upgr_4122`.`cscart_stat_sessions`.`uniq_code` = 1123279416))"
    }
  }
}

Result

sess_id
42747