SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '998954bc7f8d57fb4207364a21fd4b5296cfc85ecb9660515eb29ed7a3794edb' 
  AND token = 'atVq79leRcX9judl6B4NvA+iQ2i8derRHOLyEgEFqDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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