SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '62b2970b048a6cbd2240b506800d5f69182d934afc9bf23a05d5151617c5cb42' 
  AND token = 'HtM3HPMmMe9efHNshdxSg4pQtRt9IgZwNGe+NztuDJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}