SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '13eb3b9e4c90846dc8ed4274995d496dea24fee6867649246f458e90073db324' 
  AND token = 'JoRmByK80hSBBQpIXfzj8H19hDGIqs4DJ+x3Rh8O+qY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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