SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c31dbc9cd88ea496a7ba209356b511d6718c858b34988cf4a60659beb173df21' 
  AND token = 'J6ZzMfh/vX/oZuVIunj15LaXgxWWogLQMRm+TxzVIFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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