SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6cbb168c8aa4bd36365909b58368988556715635121ba27773a1330131e81230' 
  AND token = 'YMb3cMqTF5wS7oZbrn2i6OueZKvk/9RJy7/YVbery6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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