SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f386b29f19cda9830224a57a708bab874273b018c9a9a988f622f7027a0ee6d' 
  AND token = 'IvVMjVXvHyEpUKidYzsgOUdUgtO3Def/ArxrlNmEFz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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