SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'edb9a880e6e87797a2bb8692908e0831959deb66273ba485afbd847fa751af27' 
  AND token = '0Nn3gQ4jeXAfACaARPzLhreJ50ptNxetABBgGjOdoE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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