SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe5e5a408f8255a4151351b90c44d4166f923a37f29d67c9d36ca4880550ceb7' 
  AND token = 'alQa1VXaNvJhuxnLHiteqK+zmV+/p+Odo78vGOUabcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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