SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3842e82bd708f437b6ceffdd1d4b7135c59a6610b21de39ac21810fe7f889a40' 
  AND token = 'rERAJCvf9NaXjHg9MljcV0cpxKvuzXFsRMn32IyDdbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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