SELECT 
  bonuses 
FROM 
  cscart_promotions 
WHERE 
  status = 'A'

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "5.50"
    },
    "table": {
      "table_name": "cscart_promotions",
      "access_type": "ref",
      "possible_keys": [
        "status_idx"
      ],
      "key": "status_idx",
      "used_key_parts": [
        "status"
      ],
      "key_length": "3",
      "ref": [
        "const"
      ],
      "rows_examined_per_scan": 6,
      "rows_produced_per_join": 6,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "4.90",
        "eval_cost": "0.60",
        "prefix_cost": "5.50",
        "data_read_per_join": "5K"
      },
      "used_columns": [
        "bonuses",
        "status"
      ]
    }
  }
}