SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a9300c081aba44516e31636d2876ae9b7c81c0af1764496dfbb4d10867158d3' 
  AND token = '92tovYnHAaOYmgfA9HTtQm0YAI5quRAemokQfPVBbS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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