SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    86047, 86044, 86046, 86043, 86045, 86050, 
    86049, 86048, 86054, 86055, 86053, 
    86057, 86056, 86065, 86064, 86063, 
    86077, 86080, 86079, 86078, 86076, 
    86144, 86143, 86145
  )

Query time 0.02237

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 24,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (86047,86044,86046,86043,86045,86050,86049,86048,86054,86055,86053,86057,86056,86065,86064,86063,86077,86080,86079,86078,86076,86144,86143,86145)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}