SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbb99801392289e09a43d9cc0b838a36bdf8083260d861d84f67da571476821d' 
  AND token = 'ARsFK4qG0SzlI9Fw8tTZyHAHpUiXsZn18vsiE9KDuOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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