SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2f6dc0aab983290d23f43e4ef87a6a69717e7d141abb97c90f49113cc748f73b' 
  AND token = 'HkpgMHTCB3pwf4Xq3VsdHmbjLsySzhfDN2wi4DMzFfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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