SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3ac38600482097c6a7928afb4bcebf134e1ca474169e51a37e781210768d6085' 
  AND token = '7WAzTABHP3kL2TJsD+CBkkiHiB6B0IVy1bkx60G3UFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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