SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  fv.position, 
  fvd.variant 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_feature_variants AS fv ON pfv.feature_id = fv.feature_id 
  AND pfv.variant_id = fv.variant_id 
  INNER JOIN cscart_product_feature_variant_descriptions AS fvd ON pfv.variant_id = fvd.variant_id 
  AND fvd.lang_code = 'en' 
WHERE 
  pfv.feature_id IN (
    24191, 24498, 19986, 23496, 24219, 23321, 
    22101, 23798, 24449, 24448, 24933, 
    23320, 24634, 23795, 24658, 24657, 
    19680, 24696
  ) 
  AND pfv.product_id IN (
    37884, 44573, 5594, 41132, 33835, 41118, 
    41378, 32315, 24713, 37417, 43653, 
    48676, 32314, 45575, 37414, 46153, 
    6471, 46590
  ) 
  AND pfv.lang_code = 'en'

Query time 0.01222

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "variant_id",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "PRIMARY",
          "key_length": "6",
          "used_key_parts": ["feature_id", "product_id"],
          "rows": 343,
          "filtered": 0.489571691,
          "attached_condition": "pfv.feature_id in (24191,24498,19986,23496,24219,23321,22101,23798,24449,24448,24933,23320,24634,23795,24658,24657,19680,24696) and pfv.product_id in (37884,44573,5594,41132,33835,41118,41378,32315,24713,37417,43653,48676,32314,45575,37414,46153,6471,46590) and pfv.lang_code = 'en'",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "fv",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "feature_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "ref": ["dev_db.pfv.variant_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "fv.feature_id = pfv.feature_id"
        }
      },
      {
        "table": {
          "table_name": "fvd",
          "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": "fvd.lang_code = 'en'"
        }
      }
    ]
  }
}