SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2446b5c2ad65bdb123d5405ae71c634e3cb617318ba85d9ff29370f88d3ab7c' 
  AND token = 'dOmMhNb0t4r/AGJGhFindNJfp/2vEsIaYiJK9pY8VjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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