SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '06e17a4ff68305354a9baa92149579ac798969d554e6c19d120482a540765f6a' 
  AND token = 'b7yMYudaJPZmSZzfio7wEH2j1hOSDiNRVxrB2De/tNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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