SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '36b414d327a94605447bd6c132ad55d6d6f11613d5e7fadfc7b0c2fd92d2daf4' 
  AND token = 'pmpKvkLHNTRJ+DBkh+NdI55ltVWtWz7Tagvun5U2Q8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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