SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '343e065d3d91a758144cc3dcfa77339071f2c5d59424388e2c0ece7a0eb916db' 
  AND token = 'gh7ciL76IqEYUkppBA6Utf06beOKdUx5zSpLtPgZKK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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