SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '829d2e30871fb7ea5927915b350031444f6d5d42930d6bb4aa1b7001e722a336' 
  AND token = 'kreHzm+M5iZwGr6eyZfXvzwft9CSHV8LQ+JCrMpyfpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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