SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27ab8b8ea820ddae494fea6d70d17ae6d450940758813485b7c5e8621c859f0f' 
  AND token = 'ouifXT3sYBIxhiz6L6Keo8aWry3Fqg0rQ5/EnU/FDOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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