SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12ec3b25a5298f3aa49b74f743613d772835a83348974355ff0b06fa879f2af7' 
  AND token = 'V7G7SYe9fKzGPSssOKuddLrVfkPgHwq/72shWgFSsAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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