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

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.01034841,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_companies",
          "access_type": "index",
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["company_id"],
          "loops": 1,
          "rows": 1,
          "cost": 0.01034841,
          "filtered": 100,
          "attached_condition": "cscart_companies.`status` = 'A'"
        }
      }
    ]
  }
}