SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c743a35e7cd390b532586dcd493297107358dd6e41521acf6e6733f2020ee8cf' 
  AND token = 'F80nRhVORSC+SkXo5g89AfHd54M0GtkR/IRmLdypweA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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