SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '735244e365b402ef22eee020fe609ea41dcdf8a46a72cc7dbd9511f05dce16e9' 
  AND token = 'xAYTrrgOyEY4FdaBx7ogEdnl40AiI1NKryYIccFvwHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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