SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '68b36fdfb6ce03d24b37c42bc410de5b4b329b867e576c568f13b918716c9090' 
  AND token = 'ep38Vds38vgo5iHSPus6IWXTpBn8Px2KqwYhZiI+3/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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