SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '212488bbc00e401b659a403a6822a1c52fad6c3db9bea968d197504526ff500b' 
  AND token = 'tRr/4kwNInd7Xj7lEXkdPpCT5v8WCmic7bcjnLgNpTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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