SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1dba0ba1130f979969ccb31ce7578e67706d842a78fab2393bc3aba523b12375' 
  AND token = 'epOUwaDQWdgk/LdsauBDUqdl/EmKWVVnqrPJ8rlSDmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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