SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1aa84f89849375ecc124527df55c24ed6ee959349a616562753e2b96cead17e1' 
  AND token = 'LmGKq55ohcqm1uppByEl6xcbR6q/XtmhLyWubL6UQrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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