SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e88acf85c127a7ad181ea8041c91312a35dbbc8831436af33da48269c530f237' 
  AND token = '7JUprwNU+hbLwyvjG6Yntf0ex860WoFqGgbOGkSDiBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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