SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef76016bf0777029fc7de70c0b7737800b3c93b61ba07dafdcdf8e3d1012a31' 
  AND token = 'KExE0JF+PGyAaXx9/E4Rom1KO8VFYTD/CwTShWv5Gro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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