SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '87afe2c359749f147cdad83edf3957df04a7a64341980432707204f4a61b8fbd' 
  AND token = 'mIGO3EE9D8/B9QyXBTJHoEgnaq5SIWCE+n7aPyziAD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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