SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abe78d0d2c46e117730906c8591fdada84345aa5b7d9e2568c68560ec42af195' 
  AND token = '6ueCd5Ags1XmzJGAnZZzHKAzaeFnWFsHVmweaQGedX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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