SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9dab799df80278983077e8290ff190f9ebda320e56c94c9e33ec1170fd3b238f' 
  AND token = 'mivU7qrGimEcrHMaKtCBNu8iTAOCmtd0TgcW9PAFv9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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