SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ccc2543be0a857a98b1588cb417141174ba84ae220911c8bbd53b56c77c30cc' 
  AND token = 'KgV33KFc6wNLJsPNMsGgNg7SJH3705pAecE75s/vfeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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