SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3cfde29c224cf8f8c034524ffcb68e737f5972ebf957e25b8873290841e5e96' 
  AND token = 'AOBCuXQcP7E34wqweJuM071t0TWylQkSCbTpxPCSs+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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