SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '82dda5117abdaed30f0a38d8df3bba19de0a28a8b2770a174130be50f6c2c0a0' 
  AND token = 'q9Xlf4qFrG+3LWMs2G60gct3mTVjl5zZG2GCJdlAK20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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