SELECT 
  COUNT(*) AS cnt 
FROM 
  cscart_vendor_locations

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.45"
    },
    "table": {
      "table_name": "cscart_vendor_locations",
      "access_type": "index",
      "key": "locality_country_idx",
      "used_key_parts": [
        "locality",
        "country"
      ],
      "key_length": "292",
      "rows_examined_per_scan": 2,
      "rows_produced_per_join": 2,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "0.25",
        "eval_cost": "0.20",
        "prefix_cost": "0.45",
        "data_read_per_join": "5K"
      }
    }
  }
}