SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9bdcac74364ba31a71a922b2489390b88733495a4ee7138c362ec1ad336b77af' 
  AND token = 'a7UA3TcFoLH2DU17Kku8sXHwaI2TLHmprN8XYTJ3mL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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