SELECT 
  product_id 
FROM 
  cscart_event_products 
WHERE 
  event_id = 1 
  AND status = 'A'

Query time 0.00085

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "8.80"
    },
    "table": {
      "table_name": "cscart_event_products",
      "access_type": "ALL",
      "rows_examined_per_scan": 82,
      "rows_produced_per_join": 0,
      "filtered": "1.22",
      "cost_info": {
        "read_cost": "8.70",
        "eval_cost": "0.10",
        "prefix_cost": "8.80",
        "data_read_per_join": "23"
      },
      "used_columns": [
        "event_id",
        "product_id",
        "status"
      ],
      "attached_condition": "((`cscartdb`.`cscart_event_products`.`event_id` = 1) and (`cscartdb`.`cscart_event_products`.`status` = 'A'))"
    }
  }
}