SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bd52a54955863a0d41bc2936fe4b946ddd33eb806f867d39bbbaca36f389420' 
  AND token = 'ZHCJ2DdfzDgopG4CNDxIjKmuZjBH8pic+M+xxq0vD9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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