SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '168965d0659513b455ad1f1bea30707bd77fe08725cccba680536d75096f8f40' 
  AND token = 'QbwD9KhC4gM/fUDE8QCAsfHCBG9M0BBK+bGduqJm09g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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