SELECT 
  * 
FROM 
  cscart_product_feature_variants 
WHERE 
  variant_id IN (
    4775, 4764, 3953, 3745, 2140, 1966, 2202, 
    2331, 3709, 4862, 2747, 1934, 1913, 
    1862, 1882, 1855, 4755, 1878, 1939, 
    2470, 1987, 1880, 2426, 1874, 2667, 
    1869, 3096, 3084, 3093, 3102, 3101, 
    3090, 3086, 3087, 3686, 4969, 3089, 
    3104, 3091, 3088, 3094, 3095, 3100, 
    187, 495, 2030, 1856, 1870, 1859, 0, 
    229, 231, 723, 511, 461, 658, 17, 389, 
    388, 428, 712, 1478, 1877
  )

Query time 0.00097

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_feature_variants",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 63,
          "filtered": 100,
          "index_condition": "cscart_product_feature_variants.variant_id in (4775,4764,3953,3745,2140,1966,2202,2331,3709,4862,2747,1934,1913,1862,1882,1855,4755,1878,1939,2470,1987,1880,2426,1874,2667,1869,3096,3084,3093,3102,3101,3090,3086,3087,3686,4969,3089,3104,3091,3088,3094,3095,3100,187,495,2030,1856,1870,1859,0,229,231,723,511,461,658,17,389,388,428,712,1478,1877)"
        }
      }
    ]
  }
}