SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '307cf6896b2047f397077872f7805d62be66c56116fb9ad46d4b6dbe29672cd1' 
  AND token = '1JMdjtjE93YAwCqRruUfmqjzVAFP9hbGjJ1xZ0Fl5Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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