SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcce776816530270a34120f4a244d90104b42df0dadd5137c637bc6baa1c2684' 
  AND token = 'kfIBMqJ7973L83MmOjJwGOC1aE6oz6946ZaJSBjhtbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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