SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72346c497043fe3e61852e7d5a31f3fbe953a90d6196f00b9e969c7ed9beb958' 
  AND token = 'PCkt8jZsKCIJwrB2qvaG2MlnLiKk3eV9GHCRt35Ofow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}