SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e5875373e1246474b7e3eda6907f75bfd56a242adc258947bfbdd9f688803dd' 
  AND token = '9iQGZqpBU12SaidOff+aXQ3SewatJOIVTwog4HCim+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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