SELECT 
  company_id 
FROM 
  companies 
WHERE 
  custom_domain = 'stageuat.goimagine.com'

Query time 0.00716

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1393.49"
    },
    "table": {
      "table_name": "companies",
      "access_type": "ALL",
      "rows_examined_per_scan": 9780,
      "rows_produced_per_join": 978,
      "filtered": "10.00",
      "cost_info": {
        "read_cost": "1295.69",
        "eval_cost": "97.80",
        "prefix_cost": "1393.49",
        "data_read_per_join": "14M"
      },
      "used_columns": [
        "company_id",
        "custom_domain"
      ],
      "attached_condition": "(`goimagine`.`companies`.`custom_domain` = 'stageuat.goimagine.com')"
    }
  }
}