SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7904a85bc431e59ae5e58ee23348343e5fafb60c47485cc606fc876f3c988c7f' 
  AND token = 'b9ZsnoUi8HjSCSunewWbYRYwpY9oWki+VuUTSh5FggA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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