SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ec504b79d02288068f0ebd771839db5335011af3f7a3f7b6df41d1ded7627ac5' 
  AND token = 'iwct4NYhFhvaA1cnLxsLub1qlBOsId9n3ZPzjP23sEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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