SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '540c7cf57b41224779c3e965a741d731aff577d3ad035eb721ec1264a6806438' 
  AND token = 'MpJFnF8dhIP7HQ/QdViQVwavyvIT+G10Gms8Z+Z8BwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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