SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8f5f4760e75e2b37f12fb4fed59ae47f7dcc982465c955da4a10ee3d83aac19' 
  AND token = '6Y1H7KUFXC7ovkRnvcEc2sSwl4TG5U5hIus3ZwG6mAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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