SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '649fe78513c9a7f374719703baa629cc152d183cd2bfef8fccc9afcd32418611' 
  AND token = '+qCuJc7VEcScme1SDnw1DvdEdCsCdcjcZrOxYZ35HNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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