SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56de1411ff6afffc511bb1bc60b92e1c17bb773f975ba2eff7d3f65035486ac8' 
  AND token = '5fwiWdfdPaZpafWCJfTSuXMHilfTLSH5C9/PhdHKTjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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