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SELECT 
  * 
FROM 
  cscart_vd_vendors_relationships 
WHERE 
  brand_id = 42

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_vd_vendors_relationships",
          "access_type": "ref",
          "possible_keys": ["brand_id"],
          "key": "brand_id",
          "key_length": "4",
          "used_key_parts": ["brand_id"],
          "ref": ["const"],
          "rows": 14,
          "filtered": 100
        }
      }
    ]
  }
}

Result

id	brand_id	feature_id	variant_id	lang_code
8713	42	654	2141	es
8712	42	654	2140	es
8711	42	654	2136	es
8710	42	647	1890	es
8709	42	662	2205	es
8708	42	660	2188	es
8707	42	658	2177	es
8706	42	652	2112	es
8705	42	652	2105	es
8704	42	652	2116	es
8703	42	646	1886	es
8702	42	653	2132	es
8701	42	653	2131	es
8700	42	653	2129	es
8714	42	648	1897	es
8715	42	649	1925	es
8716	42	661	2198	es