SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '42234ba6decbd23a43d459e6f0f9f8d1f904076367c8a10e041c9b6072230914' 
  AND token = 'PJVl2c82QaE3IbaIZpfIarvPz9wxWglhumCPQRSjYhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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