SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a038d7e3d3450a71f8aa26b486ed9406fa019669379f5454c2d0ef2a2de10b6d' 
  AND token = 'KQ/zzd2tRL5AmHgm7fWOdUkDw4ydOuymdZV489Om22E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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