SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55053f63f221814f8248016fa73a382bc3e08024fe16ed07cc7341e708a9d31d' 
  AND token = 'mT05xnF266RyIwggNvoxtKRWH4ynhBNN6wspmeJQ6dM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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