SELECT 
  storefront_id 
FROM 
  cscart_hybrid_auth_storefronts_providers 
WHERE 
  provider_id = 1

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_hybrid_auth_storefronts_providers",
          "access_type": "system",
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}