SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '916d7718608bb155f8fe2e928a946410ff0ca40130a7cecfda628febbec7b4cc' 
  AND token = 'p91sbeeXp0/Im7MifkowXTllG99PvT78SfaiLAXdIRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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