SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b9968fb18090c57cc05381ab9cd23ddbafa612b2002a00ba1c57eeeb684273f' 
  AND token = 'oKTJdEMmViApktT15J0yGzZansZD+4EsVBGpCX/VEjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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