SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2f855048a0c667db6b08988080a513552d6b3cbc54935d11cc075aacddc88f55' 
  AND token = '8BtHFC0zLcaLkfEbPYg0VJFFoLKeKjeO1VNT4Gvium8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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