SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d72ab404b31e99355657e111bb28f59a3a8b765cecc3af48023177430ef440d' 
  AND token = 'USKUuqGcmysDOxnyrFBxcazSDYy/dxADklkObPhrOqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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