SELECT 
  company_id 
FROM 
  cscart_companies 
WHERE 
  status = 'A' 
ORDER BY 
  company_id 
LIMIT 
  1

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.45"
    },
    "ordering_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_companies",
        "access_type": "index",
        "key": "PRIMARY",
        "used_key_parts": [
          "company_id"
        ],
        "key_length": "4",
        "rows_examined_per_scan": 1,
        "rows_produced_per_join": 1,
        "filtered": "12.50",
        "cost_info": {
          "read_cost": "1.35",
          "eval_cost": "0.10",
          "prefix_cost": "1.45",
          "data_read_per_join": "9K"
        },
        "used_columns": [
          "company_id",
          "status"
        ],
        "attached_condition": "(`s2cart`.`cscart_companies`.`status` = 'A')"
      }
    }
  }
}