SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1af7432985dd64f8870740b7596ac3bca210d3b7d4b0ee912cbe0682a518c91' 
  AND token = 'w1PZSQnzmTtn5DYLaEnoOuB1wDHjACnFkR1nVUKPdGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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