SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a43765a96374ade3621c1cadf21291363ae72c74199260125f64c5bda2142e85' 
  AND token = 'cOWGEhJholDjHaPMl0XtsywAP4CmwjFYZUl+/rhdXBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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