SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbec493f1ef8db69c167cfda16395ffdaeb45e44e8602abc495110675fbf0c26' 
  AND token = 'aVKcQxTwTGf0+S6Yg2TcRZyuG1wvmqkCSc1zU12OYjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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