SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8aad875df1ac46f0cbea355edad79536a744ffbd1f60a48e201f61fa178d69ec' 
  AND token = '/otxaXnn96i7cGKmOKZThceBz84uboT/ARex1mfgKhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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